Luxman FL15 (mid 1960s)
The Luxman FL15 is a vacuum-tube channel divider from the mid-1960s. It is an active 2-way crossover for a 2-channel multi-amplifier setup, where separate amplifiers drive the bass and the mid/high ranges. It sold for ¥19,500 in its day.
The FL15 uses three Toshiba 12AU7 tubes in an NF-type circuit, with a passband gain of 0 dB. A changeover switch selects one of four crossover points: 100 Hz, 200 Hz, 400 Hz or 800 Hz. Each has a 12 dB/octave slope and 3 dB attenuation at the cutoff frequency. Input impedance is 70 kΩ. Output impedance is 1 kΩ or less. Maximum allowable input is 5V, with distortion of 0.2% or less at 5V output. It measures 180 × 155 × 250 mm (W×H×D).
Besides the basic two-way function, the FL15 has a connector for Luxman's "3D" system. In that system the bass of the left and right channels is summed and handled by a single speaker, which works like a subwoofer output. It also has an input level control and a balancer.
Documentation on the FL15 is thin. No precise production years, weight or frequency response range are recorded, and there are no owner reviews or service notes. A Yahoo! Auctions Japan listing for a working unit noted that power and the LOW/HIGH channel outputs were confirmed functional, but the 3D output produced crackling noise. That's common enough in 50-year-old tube gear, but not enough to call a pattern.
The FL-15 is sometimes confused with the FL-153, a different Luxman model that is a 3-way unit with 6 and 12 dB/octave slopes. The FL15 itself is strictly a 2-way design with a fixed 12 dB/octave characteristic.
Known specifications:
- Type: Channel divider (active 2-way crossover)
- Circuit: NF type, 3 × 12AU7 (Toshiba)
- Crossover frequencies: 100 / 200 / 400 / 800 Hz, selectable
- Cutoff characteristic: 12 dB/oct, 3 dB at cutoff
- Input impedance: 70 kΩ; output impedance: 1 kΩ or less
- Max input: 5V; distortion: 0.2% or less at 5V output
- Accessories: input level control, balancer, 3D output terminal
- Dimensions: 180 × 155 × 250 mm (W×H×D)
- Original price: ¥19,500
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